A ceramic fuel cell in an all solid-state energy conversion device that produces electricity by electrochemically combining fuel and oxidant gases across an ionic conducting oxide. Current ceramic fuel cells use an oxygen-ion conductor or a proton conductor as the electrolyte and operate at high temperatures (>600°C). Ceramic fuel cells, commonly referred to as solid-oxide fuel cells (SOFCs), are presently under development for a variety of power generation applications. This paper reviews the science and technology of ceramic fuel cells and discusses the critical issues posed by the development of this type of fuel cell. The emphasis is given to the discussion of component materials (especially, ZrO2 electrolyte, nickel/ZrO2 cermet anode, LaMnO3 cathode, and LaCrO3 interconnect), gas reactions at the electrodes, stack designs, and processing techniques used in the fabrication of required ceramic structures.

Ceramic Fuel Cells

Ferroelectric, dielectric and piezoelectric properties of ferroelectric thin films and ceramics are reviewed with the aim of providing an insight into different processes which may affect the behaviour of ferroelectric devices, such as ferroelectric memories and micro-electro-mechanical systems. Taking into consideration recent advances in this field, topics such as polarization switching, polarization fatigue, effects of defects, depletion layers, and depolarization fields on hysteresis loop behaviour, and contributions of domain-wall displacement to dielectric and piezoelectric properties are discussed. An introduction into dielectric, pyroelectric, piezoelectric and elastic properties of ferroelectric materials, symmetry considerations, coupling of electro-mechanical and thermal properties, and definitions of relevant ferroelectric phenomena are provided.

https://iopscience.iop.org/article/10.1088/0034-4885/61/9/002/pdf

Ferroelectric, dielectric and piezoelectric properties of ferroelectric thin films and ceramics

An overview of the state of art in ferroelectric thin films is presented. First, we review applications: microsystems' applications, applications in high frequency electronics, and memories based on ferroelectric materials. The second section deals with materials, structure (domains, in particular), and size effects. Properties of thin films that are important for applications are then addressed: polarization reversal and properties related to the reliability of ferroelectric memories, piezoelectric nonlinearity of ferroelectric films which is relevant to microsystems' applications, and permittivity and loss in ferroelectric films-important in all applications and essential in high frequency devices. In the context of properties we also discuss nanoscale probing of ferroelectrics. Finally, we comment on two important emerging topics: multiferroic materials and ferroelectric one-dimensional nanostructures. (c) 2006 American Institute of Physics.

/pdf/ferroelectric-thin-films-review-of-materials-properties-and-rc7umdkxk5.pdf

Ferroelectric thin films: Review of materials, properties, and applications

Progress in material selection for solid oxide fuel cell technology: A review

Small, light weight and multifunctional electronic components are attracting much attention because of the rapid growth of the wireless communication systems and microwave products in the consumer electronic market. The component manufacturers are thus forced to search for new advanced integration, packaging and interconnection technologies. One solution is the low temperature cofired ceramic (LTCC) technology enabling fabrication of three-dimensional ceramic modules with low dielectric loss and embedded silver electrodes. During the past 15 years, a large number of new dielectric LTCCs for high frequency applications have been developed. About 1000 papers were published and ∼500 patents were filed in the area of LTCC and related technologies. However, the data of these several very useful materials are scattered. The main purpose of this review is to bring the data and science of these materials together, which will be of immense help to researchers and technologists all over the world. The comme...

Low loss dielectric materials for LTCC applications: a review

Experimental and theoretical investigations of the electromechanical anisotropy of ceramics modified with Ca, Ni-Nb, and Mn are presented. It is demonstrated that the large anisotropy of these ceramics is neither a bulk property of the PbTiO/sub 3/-crystallites nor a domain wall effect. The anisotropy is caused by the statistical orientation of the crystallites in the ceramics and by the material properties due to this orientation. The ratio of electrostrictive coefficients and the ratio of single-crystal permittivities in these ceramics also play a decisive role. The result enables one to comprehend easily the dependence of the ceramic's electromechanical anisotropy on the material composition, the degree of poling, and the temperature. >

Anisotropic piezoelectric effect in modified PbTiO/sub 3/ ceramics

A planar multi target sputtering approach was used to deposit self polarized PZT films on TiO2/Pt bottom electrodes for the use in thin film pyroelectric IR detector arrays By using elevated substrate temperatures of about 450°C “in situ” growth of tetragonal PZT could be achieved The films exhibited pyroelectric currents without poling The pyroelectric coefficient was 2×10−4 C/m2K, the dielectric constant was 300 and dielectric loss tan δ was 001 The self polarization disappears after heating the sample to 600°C Stresses were studied in the thin film processing for the bottom electrode and the PZT film The TiO2/Pt electrode is under high tensile stress of 900 MPa after preparation PZT has a small compressive stress of -60 MPa, the whole TiO2/Pt/PZT stack has a tensile stress of +80 MPa This low stress level together with the self polarization and the good electrical properties makes the films suitable for the use in pyroelectric detector arrays

Deposition of self-polarized PZT films by planar multi-target sputtering

A planar multi-target sputtering system was used to deposit ferroelectric lead zirconate titanate (PZT) films. At substrate temperatures of about 450°C “in-situ” deposition of single phase perovskite PZT was obtained. By investigation with SEM and TEM films exhibited a columnar structure with crystallites of about 200 nm in size. The permittivity of the films varied from 450-600. The films exhibited hysteresis loops, remanent polarization of 15-20 μC/cm2 and coercive field strength of 70-85 kV/cm.

Deposition of ferroelectric PZT thin films by planar multi-target sputtering

Within a 3-year project a pyroelectric detector array based on a tetragonal Pb(Zr,Ti)O/sub 3/ (PZT) thin film on a silicon substrate was developed. Compositions of about 25-30% Zr showed best properties for the application in pyroelectric sensing systems. For the film deposition, planar multi target sputtering from 3 metallic targets in a reactive Ar/O/sub 2/ mixture is used. The advantage of this method is that the perovskite phase can be grown down to relatively low substrate temperatures of about 500/spl deg/C, a strong self polarization for compositions Zr/(Zr+Ti)<0.3 and a convenient control of the stoichiometry simply by varying the power supplied to the individual targets. The developed chip has (11/spl times/6) elements, his overall size is (8/spl times/4,7) mm/sup 2/. The array pixels of 280/spl times/280 /spl mu/m/sup 2/ have a noise equivalent power NEP of less than 0.7 nW at 1 Hz. The achieved specific detectivity D/sup */ at a modulation frequency of 10 Hz is 3/spl middot/10/sup 8/ cm/spl middot/Hz/sup 1/2//W.

Sputtering of self-polarized PZT films for IR-detector arrays

An ultrasound array has a number of oscillator elements arranged side-by-side, each oscillator element having a trapezoidal cross-section. The oscillator elements are separated from each other by incisions having non-parallel walls, which are co-planar with surfaces of the piezoelectric material comprising the oscillator element. The incisions terminate in a damping member, to which all of the oscillator elements are attached. The incisions are produced with an excimer laser whose laser beam is focused onto a prepared layered material, with the incisions proceeding along a line.

Wolfram Wersing

Papers

Anisotropic piezoelectric effect in modified PbTiO/sub 3/ ceramics

Deposition of self-polarized PZT films by planar multi-target sputtering

Deposition of ferroelectric PZT thin films by planar multi-target sputtering

Sputtering of self-polarized PZT films for IR-detector arrays

Ultrasound array having trapezoidal oscillator elements and a method and apparatus for the manufacture thereof